package com.zwd.cases.demo.exceptiondeal;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.security.SecureRandom;

/**
 * @Description AES加解密相关测试类
 * @Author zhengwd
 * @Date 2022/5/13 11:45
 **/
public class AESDemo {

    public static void main(String[] args) {
        // 加解密异常 001
        inputLengthMustBeMultipleOf16();

    }



    /*
    异常信息：
        加密前：test
        javax.crypto.IllegalBlockSizeException: Input length must be multiple of 16 when decrypting with padded cipher
            at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:936)
            at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:847)
            at com.sun.crypto.provider.AESCipher.engineDoFinal(AESCipher.java:446)
            at javax.crypto.Cipher.doFinal(Cipher.java:2165)
            at com.zwd.cases.demo.exceptiondeal.AESDemo.decrypt(AESDemo.java:110)
            at com.zwd.cases.demo.exceptiondeal.AESDemo.main(AESDemo.java:48)
        Exception in thread "main" java.lang.NullPointerException
            at java.lang.String.<init>(String.java:566)
            at com.zwd.cases.demo.exceptiondeal.AESDemo.main(AESDemo.java:49)

        Process finished with exit code 1

        分析：字符编码集可能不同
    */
    private static void inputLengthMustBeMultipleOf16() {
        /*// 有问题代码
        String content = "test";
        String password = "12345678";
        //加密
        System.out.println("加密前：" + content);
        byte[] encryptResult = encrypt(content, password);
        try {
            String encryptResultStr = new String(encryptResult,"utf-8");
            //解密
            byte[] decryptResult = decrypt(encryptResultStr.getBytes("utf-8"),password);
            System.out.println("解密后：" + new String(decryptResult));
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }*/

        // 正确处理代码
        String content = "test";
        String password = "12345678";
        //加密
        System.out.println("加密前：" + content);
        byte[] encryptResult = encrypt(content, password);
        String encryptResultStr = parseByte2HexStr(encryptResult);
        System.out.println("加密后：" + encryptResultStr);
        //解密
        byte[] decryptFrom = parseHexStr2Byte(encryptResultStr);
        byte[] decryptResult = decrypt(decryptFrom,password);
        System.out.println("解密后：" + new String(decryptResult));
    }

    /**
     * 加密
     * @param content 需要加密的内容
     * @param password  加密密码
     * @return
     */
    public static byte[] encrypt(String content, String password) {
        try {
            KeyGenerator kgen = KeyGenerator.getInstance("AES");
            kgen.init(128, new SecureRandom(password.getBytes()));
            SecretKey secretKey = kgen.generateKey();
            byte[] enCodeFormat = secretKey.getEncoded();
            SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
            Cipher cipher = Cipher.getInstance("AES");// 创建密码器
            byte[] byteContent = content.getBytes("utf-8");
            cipher.init(Cipher.ENCRYPT_MODE, key);// 初始化
            byte[] result = cipher.doFinal(byteContent);
            return result; // 加密
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**解密
     * @param content  待解密内容
     * @param password 解密密钥
     * @return
     */
    public static byte[] decrypt(byte[] content, String password) {
        try {
            KeyGenerator kgen = KeyGenerator.getInstance("AES");
            kgen.init(128, new SecureRandom(password.getBytes()));
            SecretKey secretKey = kgen.generateKey();
            byte[] enCodeFormat = secretKey.getEncoded();
            SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
            Cipher cipher = Cipher.getInstance("AES");// 创建密码器
            cipher.init(Cipher.DECRYPT_MODE, key);// 初始化
            byte[] result = cipher.doFinal(content);
            return result; // 加密
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 将二进制转换成16进制
     * @param buf
     * @return
     */
    public static String parseByte2HexStr(byte buf[]) {
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < buf.length; i++) {
            String hex = Integer.toHexString(buf[i] & 0xFF);
            if (hex.length() == 1) {
                hex = '0' + hex;
            }
            sb.append(hex.toUpperCase());
        }
        return sb.toString();
    }

    /**
     * 将16进制转换为二进制
     * @param hexStr
     * @return
     */
    public static byte[] parseHexStr2Byte(String hexStr) {
        if (hexStr.length() < 1)
            return null;
        byte[] result = new byte[hexStr.length()/2];
        for (int i = 0;i< hexStr.length()/2; i++) {
            int high = Integer.parseInt(hexStr.substring(i*2, i*2+1), 16);
            int low = Integer.parseInt(hexStr.substring(i*2+1, i*2+2), 16);
            result[i] = (byte) (high * 16 + low);
        }
        return result;
    }
}
